dog777 wrote:
hi, i am new to building and soldering pc boards. i love tubes and the sound produced by tubes. i am definitely thinking of building this and have a few questions on it. first, i know what a R1 100k, 1/4W is ,but what is a 150, 1/4W?? i cant find this on the radio shack website at all including the 10, 1/4W.

the other things are located in radio shack but id dunno what a 150, 1/4W or a 10, 1/4W is. if you can explain if it is a resistor and why it doesnt have a K at the end, please explain to me. thanks! onother question is that the resistors, do they have to be metal-film? if so which ones? thanks so much!! i love the concept!!!
Thanks everyone for the explanations, Pat, if you pick up this pack Part # 271-309 from Radio Shack. It will include the 100k, 10, 150 and 4.7k (4k7) that are used in the amp. The pack is about $5 and they are all metal film. Metal film is not necessary, just that this is a convenient pack to get them all at once. There are arguments that metal film is sonically superior, but since this amp is operating at such a low level the difference is negligible.
A 4.7K can be used in place of the trim potentiometer to set current through the tube and the bias for the mosfet. 4.7k will set the bias at around 6~7 volts.
The wonderful thing about this amp is you can use pretty much what you have. You can get away with a 100 ohm cathode resistor, if using a trim pot at the anode, just adjust until the gate of the mosfet is half of the B+. Heck you can even omit the cathode resistor if you do not have one. The amp can run straight common cathode, but I have decided on 150 because of the bias point and there are some in the radio shack multipack.
Have fun
Rogers